Many modern wireless communication systems are logically divided into a bearer plane and a control plane. The bearer plane may transport bearer traffic. Examples of bearer traffic include voice and/or data communication originating from or heading to a wireless communication device (WCD), such as a mobile phone. The control plane may transport control traffic on behalf of the WCD. This control traffic may facilitate the establishment, maintenance, and tear down of the WCD's bearer sessions. Accordingly, the control plane may include one or more nodes acting as policy decision points. These nodes may transmit, receive, or manipulate control traffic on behalf of the WCD.
One role that these policy decision points may take on is to determine when and how to insert a filter into the WCD's bearer path. Filters may serve many different functions, including, but not limited to, allowing the WCD to communicate with certain correspondent nodes, preventing the WCD from communicating with other correspondent nodes, controlling which applications a WCD may use, redirecting some or all of the WCD's communication to a particular correspondent node, or applying a quality of service (QOS) treatment to the WCD's communication. It may be advantageous to insert a particular filter into a particular node in the WCD's bearer path in cases where this particular node may be best equipped to apply the filter in an efficient fashion.
One challenge in deploying wireless communication networks is to support handoffs of WCDs from one wireless coverage area to another wireless coverage area. The mobile Internet Protocol has been developed to support handoffs between wireless coverage areas, for data communication sessions involving the Internet Protocol (IP). Mobile IP involves a WCD registering with a foreign agent and a home agent during its initial access to the wireless communication network, and during at least some handoffs. Foreign agents may be associated with certain wireless coverage areas or groups of wireless coverage areas, while home agents may anchor the WCD's mobile IP session. Thus, when a WCD is handed off from one wireless coverage area to another, the WCD may register with a different foreign agent, but preferably maintains its registration with the same home agent. Accordingly, all of the WCD's communication may pass through the home agent. Consequently, even as the WCD is handed off between wireless coverage areas (and thus between foreign agents as well), the home agent can apply a consistent policy to the WCD's communication.
Therefore, it may be advantageous to deploy a filter for a WCD into the WCD's home agent. To do so, some proposals have involved the home agent accessing an authentication, authorization, and accounting (AAA) server during the WCD's mobile IP registration process to (i) authenticate the WCD, and (ii) acquire any filter to be applied to the WCD's communication. However, prior to the home agent becoming involved in the WCD's mobile IP registration process, a foreign agent may have already authenticated the WCD. Additionally, a wireless service provider may support a large number (e.g., tens of millions) of WCDs, but only a small fraction of these WCDs may be subject to filtering.